In general, a water and light resistant ink composition for use in recording exemplified by an ink composition for use in writing instruments are divided into two groups. The first is an oil base or organic solvent base ink composition, and the second is a water base ink composition. The oil base ink composition contains a dye which is soluble in an organic solvent, but is insoluble in water, and it has an advantage that it can write on an impervious surface such as of glass or resin as well as on a pervious surface such as of paper. However, the oil base ink composition usually contains an aromatic hydrocarbon such as xylene or toluene as the organic solvent, and consequently there is a fear that such a solvent might be injurious to the health. In addition, the oil base ink composition has a disadvantage that when it is used to writeon paper, it readily penetrates or permeates through the paper to the back.
In turn, the conventional water base ink composition uses a water insoluble pigment as a colorant, so that it has no such a problem as involved in the oil base ink composition. However, the conventional water base pigment ink composition has a disadvantage that the pigment used precipitates with time to cause color separation, or a porous pen tip is clogged, or a writing formed therewith has no sufficient darkness when used in a marking pen.
Thus, in the production of water base ink composition containing a water soluble dye as a colorant, the employment of a direct dye, or an additive such as a wetting agent, has been heretofore proposed in order to make a writing formed therewith water resistant. However, there has not yet been developed such a water base dye ink composition which forms a sufficiently water resistant writing on a pervious writing surface such as paper.